The New York Times reports on the article published today in the Journal of Neuropathology and Experimental Neurology describing the brains of three athletes with histories of head injuries who had an illness that looked like Amyotrophic Lateral Sclerosis (ALS).
ALS, which has been associated with Gehrig’s name since he was diagnosed with the disease in 1939, is a devastating and currently incurable illness. Motor neurons (brain cells that control muscle movement) degenerate and die, leading to a progressive paralysis that eventually robs people of the ability to breathe on their own. The illness forced Gehrig to retire from baseball immediately, and he died two years later, at the age of 37.
The group publishing this paper is led by Dr Ann McKee of the Center for the Study of Traumatic Encephalopathy at Boston University. (Their article is available here.) It’s the same group that has described a connection between repeated head injury in football and problems ranging from intellectual decline to depression.
And now they suggest an association between head injuries and a motor neuron disease that looks like ALS.
Gehrig’s history comes up in the context of this research not just because the disease carries his name. He was known — paradoxically — for his durability. He played in 2130 consecutive games (a record that stood for more than 50 years). It is also known that he played several times after being knocked unconscious. Some people familiar with his sports history surmise now that his motor neuron disease may have been related to his head injuries.
Since this paper reports on only three cases, it’s tough to draw many conclusions from it. It is probably not enough evidence to change the historical view of Gehrig’s illness.
But the findings do underscore an important principle to keep in mind when thinking about many neuropsychiatric diagnoses. Relatively narrow terms like ALS — but also broader ones like major depression — refer to syndromes where the root causes and the neurobiology are not very well worked out. That is, two people can have illnesses that look similar, but the underlying pathology can be quite different. This principle is as true for common illnesses — for example, depression in its various forms or schizophrenia — as it is for rare illnesses like ALS.
Anything that illustrates the complexities of brain function is a good thing. There is not just one depression. There isn’t one schizophrenia. And my bet is that there is not one ALS either.
The full reference for the Mckee et al paper (available at their website at http://www.bu.edu/cste/news/academic-articles/) is
McKee AC, Gavett BE, Stern RA, Nowinski CJ, Cantu RC, Kowall NW, Perl D, Hedley-Whyte ET, Price B, Sullivan C, Morin P, Lee HS, Kubilus CA, Daneshvar DH, Wulff M, Budson AE. TDP-43 Proteinopathy and Motor Neuron Disease in Chronic Traumatic Encephalopathy. J Neuropath Exp Neurol, 2010; 69(9): 918-929.